Increasing numbers of parents will defy government recommendations this autumn and take their children out of school to ensure an affordable - and sunny - summer holiday.

A new survey from Tesco Travel Money finds that almost one in five families is planning to go away in term time, a trend fuelled by the combination of the recession's squeeze on family finances, and the washout British summer weather.

"It's definitely snowballing as parents see other families snapping up cheap deals and want to do the same," says Emma Cripwell, a spokeswoman for Kids in the Med (0845 277 3300; kidsinthemed.co.uk). "Our bookings are up 10 per cent on this time last year."

Cripwell believes that European hoteliers and resorts are realising that there is a new market to tap into and are offering family discounts outside the school holidays. The Sani Resort in Greece, for example, is offering a 20% accommodation discount and a kids stay free offer, valid from 28 August - a saving of £1,103 for a family of four.

"It's a no-brainer," says Cripwell. "Particularly as many parents feel that their kids learn as much by spending a week abroad as they would in the classroom."

Holidays in term time are heavily disapproved of by schools. Legally, all children are allowed 10 days out a year, but schools have to grant permission, and if families fly off in defiance of a school, the child's absence is marked as "unauthorised". Parents can then be fined up to £100 - rising to £2,500 if the fine remains unpaid.

But it seems the trend is only likely to increase. A recent poll from parenting website mumsnet.com found that over 50% of parents intend to take their children out of school on a beach holiday. "The majority of families just can't afford school holiday prices," says Justine Roberts, co-founder of Mumsnet.